Mixer, particularly a concrete mixer



June 29, 1965 P. AUGUST 3,191,914

MIXER, PARTICULARLY A CONCRETE MIXER Filed May 14. 1962 V 3 Sheets-Sheet 1 June 29, .1965 P. AUGUST MIXER PARTICULARLY A CONCRETE MIXER 5 Sheets-Sheet s Filed May 14, 1962 INVENTOR. fiat, 19:

United States Patent Claims. (51. 259-160) The present invention refers to certain new and useful improvements in mixers, more particularly in concrete mixers of the type comprising a tub lift with the lifting bucket or tub constructed as a mixing trough and provided with a rotary stirring device, and a pair of guide rails for said tub.

This type of mixeris known. These known mixers first of all are disadvantageous insofar as the driving power for lifting the charged mixing trough is rather high. This is due to the fact that the mixing trough Which is conveniently guided by two pairs of rollers in co-operation with the said guide rails has to make for the discharge of its contents a rotating movement around an axis situated at a level lower than that of said mixing trough, so that the latter not only has to be lifted, but

also has to be caused to rotate around said axis. This,

situation is neither improved by providing the guide rails with bent portions and by causing said rollers to move along said bent rails.

The known mixers of the type referred to, on the other hand, are advantageous insofar as their output as compared with other mixer types, such as the known drum, plate or screw mixers, is very high, because while the mixing trough is charged at its lower position it already starts the mixing operation and finishes the same during its upward movement to its discharging position. The lift mixers proved to be able to employ for receiving, mixing and discharging a batch at a time of from about 35 to 45 seconds only. However, practice has taught that a manual control of the different operation steps within a total time of less than a minute is absolutely impossible. Therefore, the said known mixers operate with automatic controls for the main functions of the machine which, however, proved to be insufiicient and made it necessary to intentionally decrease the output or to have the machine additionally controlled by a workman. This particularly refers to the supply of the concrete mixer with the required water and to the withdrawal of the mixed and discharged concrete.

The present invention aims at avoiding these disadvantages and at improving the mixers of the type referred to in other respects so as to provide a mixer, particularly a concrete mixer capable of operating in an entirely automatic manner with a very high output, with a decreased power input and with a maximum of reliability.

Thus the main object of the present, invention is to provide a mixer, particularly a concrete mixer, of the type comprising a tub lift with a bucket or tub constructed as a mixing trough and provided with a rotary stirring device, and a pair of guide rails for said liftable mixing trough, wherein not only the motor for operating a known winch for lifting and lowering said mixing trough, but also a water supplying and proportioning device are automatically controlled by control means directly or indirectly operated by said mixing trough and the movements of this mixing trough in turn are at least in part made dependent of the capacity of operation of said water supply device and eventually also of the condition of a concrete-storing receptacle by additional control means.

I The motor for operating the winch of the liftable mixing trough is an electric motor, conveniently provided with a brake which automatically becomes operative as soon as the motor is stopped by disconnection. In certain cases said motor may also be a pole-changing motor capable of operating, when the liftable mixing trough moves downwards, with the double speed of its operation when said trough is lifted.

The winch-operating motor may at the same time operate the stirring device in the liftable mixing trough. In certain cases, however, it may be desirable to drive said stirring device independently and preferably by means of a pressure oil operated engine.

The guide rails for the liftable mixing trough preferably consist of two pairs of superposed rails of U- shaped cross section, of which the upper rails extend in straight direction throughout their length, whereas the lower rails branch off at certain distance from the upper ends of said straight rails. It is also possible to provide but one pair of U-shaped rails, in which case the upper leg of the U-shaped cross section of each rail extends in straight direction, whereas the lower leg branches off and forms a U-shaped rail branch. In bothcases one pair of the guide rollers of the liftable mixing trough in its upper position is shifted by said rail branches, whereas the other pair of guide rollers continues travelling along the'straight rails. Due to this arrangement the mixing trough in its upper position for the discharge of the prepared mixture is caused to rotate around the axis of said other pair of rollers which preferably coincides with that of the stirring device in the mixing trough and this operation requires less power than a rotation around the axis of the first-mentioned pair of guide rollers.

According to one advantageous feature of the invention, the mixer comprises in the upper zone of the lift way of the mixing trough an elastic means, preferably constituted by a spring-loaded bar which, on one hand, operates a switch controlling the winch-driving motor and, on the other hand, initiates the return movement of said mixing trough to its lower position.

The water supply means of the mixer according to the invention comprises a water reservoir connected by way of a float valve with a source of water and a measuring vessel containing an adjustable displacer in form of a plunger, the two vessels being interconnected and said measuring vessel being connected with a jet pipe for spraying water into the mixing trough, these connections being controlled by a three-way cock. The operating lever of this cock is controlled by the mixing trough through mechanical, electrical, electro-magnetic or hydraulic means, and the float valve of the said water reservoir is operatively connected with a transmitting switch which by means of a stop switch disconnects the winchdriving motor during the downward movement of the mixing trough in case of lack of water in the said two vessels. 7

The concrete-storing receptacle provided in accordance with the invention is arranged at a point situated below the upper discharging position of the mixing trough; the same is elastically suspended and when it is completely filled, by means of a contact and of a stop switch disconnects the winch driving motor before the mixing trough reaches its discharging position.

According to an additional feature of the invention this lift mixer is advantageously combined with a known screw mixer so as to deliver to the latter proportioned and pre-mixed materials.

The invention will now be described in detail with particular reference to the accompanying drawings which by way of example only illustrate two preferred embodiments of the improved mixer.

On these drawings:

FIG. 1 is a schematic side view of a first embodiment of the mixer according to the invention;

FIG. 2 is a vertical sectional view of a water supplying and proportioning device;

FIG. 3 is a schematic side View of a second embodiment of the invention combined with a known screw mixer;

FIG. 4 is a front view of the machine according to FIG. 3 as seen from the end of its mixing trough in its lower position; and

FIG. 5 is a schematic side view of a rod system for operating the water supplying and proportioning device.

The mixer according to the invention in its embodiment as shown in FIG. 1 comprises a machine frame composed of a pair of base bars 1, of vertical stays 2, 3, of a pair of upper beams 4, of an inclined guide 5 and of t-russings 6. The lift guide 5 is formed by at least one pair of rails (FIG. 3) and conveniently by two pairs of rails 7, S which through about two thirds of their length are superposed. In the upper third of their length the lower rails branch off. The rails are of U-shaped cross section. The upper trails guide the rollers 9 loosely mounted on the shaft 11 of the stirring device (not shown) in the mixing trough 10. The lower rails 7 guide the rollers 12 loosely mounted on the axle 13. The stirring device in the trough is conveniently operated by an engine indicated at 14 and suitably secured to the back of said trough. Said engine preferably is a hydraulic motor.

The mixing trough 10 has an opening 15 for charging purposes and a funnel-shaped outlet 16 for discharging the trough contents.

The winch mechanism for lifting and lowering the mixing trough 10 comprises a rope, preferably a pair of ropes -17, an engine, conveniently an electric motor indicated at 18, and a crank lever switch 19 adjacent a rope return pulley 20, the arrangement being such that said switch 19 disconnects the motor 18 as soon as the mixing trough 10 reaches its lower position and the rope 17 passing around the return pulley 20 becomes slack and the rope portion which thus moves downward beyond said pulley, operates the crank lever 19' and thereby the switch 19. The connection of the motor for hoisting the mixing trough is effected by a switch (not shown) which in a known manner may be provided on or operated by the trough-charging device, such as a scraper.

The pair of upper beams 4 carries a water supplying and proportioning device (FIG. 1), details of which have been illustrated in FIG. 2. The device 25 comprises a water reservoir 26 and a proportioning or measuring vessel 27. The reservoir 26 by way of a pipe 28 is continuously supplied with water independently of the proportioning process until the level 29 causes the float valve to shut off the water supply.

The measuring vessel 27 contains a displacer body 31 slidably mounted on a guide rod 32 so as to be able to be displaced up and down as indicated by the arrow 33 and to be fixed at a desired level by suitable known means (not shown). Between the bottom 34 of the vessel 27 and the bottom 35 of the displacer 31 there is formed a measuring chamber 36 the capacity of which changes in accordance with the adjustment in height of said displacer and represents the volume of water to be periodically delivered to the mixing trough 10.

Between the inner wall 37 of the measuring vessel and the wall 38 of the displacer 3 1 there is provided an annular gap 39 which allows the water in said vessel to reach a level indicated at 40 corresponding to the water level 29 in the water reservoir 26.

Below the measuring vessel 27 a three-way cock 42 is connected with said vessel by way of a conduit 41 of a large cross sectional area and by way of pipes 43 and 44 which also have a relatively large cross sectional area with the reservoir 26 and with a jet or nozzle pipe (FIG. 1), respectively.

The position of the lever 45 of the cock 42 determines the flow direction through the latter. In its position indicated by the reference numeral 46 the three-way cock establishes the connection between the reservoir 26 and the measuring vessel 27. In this position of the cock the vessel 27 is re-filled after each water supply to the mixing trough. In the position of the lever 45 indicated by the reference numeral 47, the pipe 43 is closed and the connection is established between the vessel 27 and the pipe 44 so that now the volume of water measured in said vessel is delivered to the mixing trough 10.

The lever 45 of the three-way cock 42 is connected with a rod system indicated at 48 (FIG. 2) so arranged that when the mixing trough 10 reaches its lower position FIG. 1), it moves the lever 45 to its position 47 so that now the water is delivered to the mixing trough, whereas when this trough starts moving upwards, it returns the cock lever 45 to its position 46, preferably with the assistance of a tension spring 49, thereby establishing the connection between the vessels 26 and 27, so that during the upward movement of the mixing trough 10 the measuring vessel 27 is filled again. The rod system 48 includes, as shown in FIG. 5, a lever connected at its upper end to the cock lever 45 and pivoted intermediate its ends at 111 on the supporting frame of the mixer. Connected to the lower end of lever 110 by means of a tie rod 112 is a crank lever 1-13 pivoted at 114 on the frame. The arm 113a of the crank lever 113 is arranged to be engaged by the mixing trough 10 when the latter moves to its lower charging position to tilt thereby the crank lever 113 in clockwise direction and to move thereby the arm 45 of the cock from the position 46 to the position 47.

Instead of mechanically operating the three-way cock 42 by means of the rod system 48, it is, of course, possible to control the same by means of a servomotor, electromagnetically or hydraulically from the mixing trough 10 when this trough reaches and leaves its lower position. It is of particularly importance that the measured quantity of water is discharged from the vessel 27 and delivered to the mixing trough 10 within a time as short as possible. Independently of the cross section of the supply pipe 28, the cross sectional area of the pipes 41 and 44 must be for all events such that the quantity of water contained in the measuring vessel 27 is discharged therefrom within a few seconds. The pipe 44 as already mentioned is connected with a jet or nozzle pipe 5%) which extends throughout the length of the mixing trough 10 and is supported by stays 51 secured to the rails 8.

The float valve 30 in the water reservoir 26 acts by way of a transmitting switch 53 upon a stop switch 52 arranged on a rail 8 at certain distance from its upper end. As long as this stop switch 52 does not receive from the transmitting switch 53 the message that the vessels 26 and 27 are filled, said switch 52 is operated by the downwards moving trough 10 so as to disconnect the motor 18 and thereby stops the trough in its downward movement. The mixing trough 10 is released and allowed to continue moving downwards as soon as the switch 52 is rendered inoperative by the transmitting switch 53 in the moment in which the vessels 26, 27 are re-filled, i.e., in which the vessel 27 contains the quantity of Water required for the next mixing operation.

Below the bent portions 7' of the lower rails 7 projecting in substantially horizontal direction there is provided a concrete-storing receptacle 55 (FIG. 1) capable of receiving one or more batches of prepared concrete. This receptacle 55 is so arranged that from the mixing trough 10 in its discharging position the concrete falls directly into said receptacle. This receptacle 55 is pivotally suspended at 56 and at its opposite side is carried by springs 57. It may also be supported at both sides by such springs if desired. These springs have such a prestress that they yield under the pressure of the completely filled receptacle. Then they act upon a contact 58 which is connected with a stop switch 59 arranged on one of the rail portions 7'. When the concrete-storing receptacle 55 is completely filled and unable to receive a further batch, as soon as the mixing trough reaches and operates the switch 59, i.e., just before it reaches its discharging position, said switch disconnects the motor 123 and thereby stops the mixing trough 10 and connects said motor again as soon as the receptacle 55 has been at least partially emptied and placed in condition for receiving a new batch of concrete.

The embodiment according to FIGURES 3 and 4 comprises the combination of the lift mixer according to the invention with a known-screw mixer of the type comprising a pair of carrier wheels 61 and a composite trough mounted on said wheels and being composed of a charging trough 62 and a mixing trough 6-3. A composite screw (not shown) extends longitudinally through the trough portions '62 and 63 and comprises in the c'harg ing trough portion, 62 a proportioning conveyor screw and in the mixing trough portion 63 a mixing conveyor screw. The-two screws of known construction are fixedly mounted on a common shaft 66 which is operated by a motor 64 and a suitable transmission 65. This screw mixer is as stated of known construction and is not claimed assuch.

According to the embodiment of the invention (FIGS. 3-4) the said screw mixer is combined with a hoisting device for a liftable mixing trough 67. The hoisting device is supported at its upper end by suitable stays 68 secured to the mixing trough 63. The hoisting device comprises a pair of parallel rails 69 and 70 of U-shaped cross section so arranged that the grooves formed thereby are open in opposite directions one towards the other. These grooves constitute guide means for rollers 71 and 72 loosely mounted on a common axle or on individual axles which in a suitable known manner by means of hearings or the like are connected with the mixing trough 67 so that the latter is guided in its lifting and lowering movements between the rails 69 and 70.

The upper legs of the U-shaped rails 69, 70 form guide surfaces 73, 74 for rollers 78, 79 and lie on an inclined plane which in the working position of the machine form with the horizontal line, e.g., with the ground 7-5 an angle on, whereas the lower legs of said U-shaped rails form branches projecting therefrom under an angle of about 90 and :also having a U-shaped cross section.

In the embodiment as illustrated the rollers 78 and 79 provided each with a wheel flange 77 are mounted on the shaft 80 of the not shown stirring device arranged in the liftable mixing trough 67, which means that the shaft 80 carries at the same time the rollers 78 and 79. On the same shaft there are provided two rope pulleys 81 and *82 carrying the ropes 83 and 84, respectively. One end of each of these ropes is fixedlat a fixed point 85 situated beyond the point of discharge of the liftable trough 67, whereas the opposite ends of Said ropes are fastened on a rope drum 86 which by mean-s of a transmission chain 87 is operated by a motor 88 with reduction gear.

After charging the liftable mixing trough 67 with the materials to be mixed, the rope drum 86 is caused to rotate 'by connection of the driving and braking motor 88, i.e., an electric motor provided with a brake which automatically operates as soon as the motor is stopped, whereby the mixing trough 67 is moved in the direction of the arrow 89 without changing its position. In its upward movement the rollers 71 and 72 are guided in the grooves formed by the U-shaped rails '69 and 70, whereas the rollers 78 and 7-9 travel along the upper surfaces 73 and 74 of said rails. in view of the fact that in the embodiment as illustrated the rollers 78 and 79 are fixedly mounted on the shaft of the stirring device in the mixing trough, this stirring device is caused to rotate while the trough moves upwards in the direction of the arrow 89. A separate driving motor for the stirring device is therefore, not required in this .case.

the pertinent oil pump being operated by a second electric motor.

When the liftable mixing trough 67 approaches its upper position, the bends 9t) cause the rollers 71 and 72 to move into the branches 73, 74, whereby as the drum 86 continues rotating and the rollers 78 and 79 move along the rail extensions 91, the mixing trough is caused to rotate around the shaft 80. Consequently the charging opening 92 of the trough moves in the direction of the arrow 93 and the contents of the trough 67 start falling into the charging trough 62 of the screw mixer 61-66.

During this rotation of the mixing trough 67 around the shaft 89 a nose member 94 or the like fixed on the shell of the trough contacts the free end of a bar 95 guidedin a cylinder 96 which is pivotally mounted at 97. Thereby the bar is pushed backwards into the cylinder 96 and compresses a spring 93 which reaches its condition of maximum compression when the liftable mixing trough is in its upper discharging position. This position is shown in FIG. 3 in dot-and-dash lines. The angle of rotation of the cylinder 96 is limited by a' stop member 99. An end disk 109 of the bar 95 operates a switch 101 which, when pushed, stops the driving motor 88 of the rope drum 86 and thus the upward movement of the liftable trough is finished. The energy accumulated in the compressed spring 98 is now set free and pushes the bar 95 and by means of the latter the nose 94 and the trough 67 so as to initiate its return in the opposite direction of the arrow 89; thereby the direction of rotation of the rope drum 86 and its driving means is also reversed. At the same time the rollers 71 and 72 are guided again into the main portions of the rails 69 and '70.

Since the angle a is relatively small in the embodiment shown in FIGS. 3 and 4 and the inclination of the rail surfaces 73, 74 is not so steep, it is not necessary to brake the lowering trough 67. It is suflicient to brake the same by suitable known means just before it reaches its lower position.

Of course, the component parts, i.e., the liftable mixing trough, the winch mechanism, etc. of the lift mixer may also be of different construction. For instance, as shown in the first embodiment of the invention, it is not necessary to combine the lift mixer with the screw mixer, although this sometimes may be advantageous insofar as the materials are delivered to the charging trough 62 in premixed condition. The supply of water proceeds in the manner described in the first embodiment, but it may also be realized by means of a pipe 104 parallel to the axle of the wheels 61, said pipe being provided with one or more rows of perforations capable of projecting the water against a hood or like member 105 which deflects it downwards into the mixing trough of the screw mixer 61-66. In case the water supply device 25 (FIG. 1) is used in this second embodiment, the same is arranged on the top of the machine, i.e., at the upper end of the stays 68 (FIG. 3).

On the other hand, the elastic means 95, 96, 98 in combination with the switches 101, 102 are conveniently incorporated in the embodiment according to FIGS. 1 and 2.

When the embodiment of the lift mixer according to FIGS. 3 and 4 are not combined with a screw mixer 6166, the same is practically identical with that of FIGS. 1 and 2, and in such case it is also provided with the control means 19, 52, 57, 58, substantially as described with reference to the embodiment according to FIGS. 1 and 2.

What I claim is:

1. In an automatic mixer, particularly a concrete mixer, in combination, a mixing trough; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an upper discharge position; a concrete storing receptacle adjacent the upper end of said path for receiving concrete from said mixing trough when the latter is in said discharge position; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is substantially filled and for continuing operation of said lifting means to move said mixing trough to said discharge position when said storing receptacle is substantially empty.

2. In an automatic mixer, particularly a concrete mixer, in combination, a mixing trough; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an upper discharge position; a concrete storing receptacle adjacent the upper end of said path for receiving concrete from said mixing trough when the latter is in said discharge position, said storing receptacle being yieldably mounted on said combined support and guide means for movement between a rest position and a displaced position; resilient means operatively connected to said receptacle and yieldably maintaining the same when substantially empty in said rest position while permitting said receptacle to move to said displaced position when substantially filled; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is substantially filled and for continuing operation of said lifting means to move said mixing trough to said discharge position when said storing receptacle is substantially empty, said control means including switch means controlled by the movement of said receptacle between said positions thereof.

3. In an automatic mixer, particularly a concrete mixer, in combination, a mixing trough; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an upper discharge position; a concrete storing receptacle adjacent the upper end of said path for receiving concrete from said mixing trough when the latter is in said discharge position, said storing receptacle being yieldably mounted on said combined support and guide means for movement between a rest position and a displaced position; resilient means operatively connected to said receptacle and yieldably maintaining the same when substantially empty in said rest position while permitting said receptacle to move to said displaced position when substantially filled; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is sub stantially filled and for continuing operation of said lifting means to move said mixing trough to said discharge position when said storing receptacle is substantially empty, said control means including a switch adjacent the upper end of said path for controlling said lifting means and contacted by said mixing trough before the latter reaches its discharge position, and contact means connected to said switch and controlled by the movement of said receptacle between said positions thereof for stopping further lifting movement of said mixing trough when the latter contacts said switch and when said receptacle is in said displaced position while permitting movement of said mixing trough beyond said switch to said discharge position when said receptacle is in said rest position.

4. In an automatic mixer, particularly a concrete mixer, in combination, a mixing trough; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an .upper discharge position; a concrete storing receptacle adjacent the upper end of said path for receiving concrete from said mixing trough when the latter is in said discharge position; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge position; pivot means supporting said storing receptacle adjacent said upper end of said path on said combined supporting and guide means for tilting movement between a rest position and a turned displaced position, said pivot means being arranged to one side of the center of gravity of said storing receptacle so that the latter will tend to tilt to said displaced position; prestressed spring means operatively connected to said receptacle for yieldably holding the same when substantially empty in said rest position, said spring means yielding when said receptacle is substantially filled so that the latter, when filled, will tilt to said displaced position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is substantially filled and for continuing operation of said lifting means to move said mixing trough to said discharge position when said storing receptacle is substantially empty, said control means including switch means controlled by the movement of said receptacle between said positions thereof.

5. In an automatic mixer, particularly a concrete mixer, in combination, a mixing trough having a forward discharge end, a first pair of guide rollers aligned along a first common axis adjacent said discharge end, and a second pair of guide rollers aligned along a second common axis rearwardly and parallel to said first common axis; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an upper discharge position, said combined supporting and guide means including a pair of upper substantially straight upwardly inclined guide rails engaged by and guiding said second pair of rollers and a pair of lower guide rails extending with a lower portion thereof substantially parallel to said upper guide rails and having an upper portion extending in substantially horizontal direction away from said upper pair of guide rails, said lower guide rails being engaged by and guiding said first pair of rollers so that said mixing trough is tilted when it reaches said discharge position to be adapted to discharge concrete therein through said discharge opening; a concrete storing receptacle adjacent to the upper end of said path for receiving concrete from said mixing-trough when the latter is in said discharge position; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is substantially filled and for continuing operation of said lifting means to move said mixing trough to said discharge position when said storing receptacle is substantially empty.

6. In an automatic mixer, particularly a concrete mixer, in combination, a'mixing trough having a forward discharge end, a first pair of guide rollers aligned along a first common axis adjacent said discharge end, and a second pair of guide rollers aligned along a second common axis rearwardly and parallel to said first common axis; upwardly inclined combined supporting and guide means for supporting and guiding said mixing trough along an upwardly inclined path between a lower charging position and an upper discharge position, said combined supporting and guide means including a pair of upper substantially straight upwardly inclined guide rails engaged by and guiding said second pair of rollers and a pair of lower guide rails extending with a lower portion thereof substantially parallel to said upper guide rails and having an upper portion extending in substantially horizontal direction away from said upper pair of guide rails, said lower guide rails being engaged by and guiding said first pair of rollers so that said mixing trough is tilted when it reaches said discharge position to be adapted to discharge concrete therein through said discharge opening; a concrete storing receptacle adjacent to the upper end of said path for receiving concrete from said mixing trough when the latter is in said discharge position; lifting means operatively connected to said mixing trough for lifting the same from said lower charging to said upper discharge'position, said lifting means including an electric motor, a rope connecting said motor with said mixing trough and a return pulley for said rope, said rope being slackened when said mixing trough is in said lower charging position to extend with a portion thereof downwardly beyond said return pulley; first switch means located adjacent the upper end of said upper guide rail for controlling the downward movement of said mixing trough along said guide rails; second switch means located beneath said return pulley and operated by said portion of said rope for stopping the electric motor when said mixing trough reaches its lower charging position; and control means controlled by the amount of concrete in said storing receptacle and operatively connected to said lifting means for stopping operation of said lifting means shortly before said mixing trough reaches its discharge position when said storing receptacle is substantially filled and for continuing ly connected to said water supplying means and said lifting means for preventing return of said mixing trough from said discharge to said charging position when the water supplying means is empty while causing return of said mixing trough to said charging position when said water supplying means is filled.

8. An automatic mixer as set forth in claim 7 wherein said lifting means includes an electric motor and wherein said additional control means includes a stop switch arranged adjacent to the upper end of said path for controlling said electric motor to prevent downward movement of said mixing trough, and a control switch controlled by the amount of water in said water supplying means and connected to said stop switch to control the latter in a manner permitting downward movement of said mixing trough only after said water supplying means is filled.

9. An automatic mixer as set forth in claim 8 wherein said water supplying means includes a water reservoir, a measuring vessel containing a displaceable and adjustable plunger body, means providing communication between said reservoir and said vessel and including a three-way cock movable between a first position providing communication between said reservoir and said vessel and a second position providing communication between said vessel and said conduit means for feeding a measured amount of water from said vessel through said conduit means into said mixing trough, and spring means operatively connected to said cock and biased to yieldably maintain the latter in said first position; said automatic mixer including further means operatively connected to said cock and operated by said mixing trough in said lower charging position for moving said cock against the force of said spring means from said first to said second position.

10. An automatic mixer as set forth in claim 9 and including a supply conduit for feeding water into said reservoir; and a float valve in said reservoir for controlling said supply conduit, said control switch being connected to said float valve to be operated thereby.

References Cited by the Examiner UNITED STATES PATENTS 1,533,950 4/25 Schlich 295-X 1,649,603 11/27 Lichtenberg 259--163 1,753,324 4/30 Webb 259163 FOREIGN PATENTS 1,092,437 11/54 France.

23,342 1905 Great Britain.

WALTER A. SCHEEL, Primary Examiner, 

1. IN AN AUTOMATIC MIXER, PARTICULARLY A CONCRETE MIXER, IN COMBINATION, A MIXING TROUGH; UPWARDLY INCLINED COMBINED SUPPORTING AND GUIDE MEANS FOR SUPPORTING AND GUIDING SAID MIXING TROUGH ALONG AN UPWARDLY INCLINED PATH BETWEEN A LOWER CHARGING POSITION AND AN UPPER DISCHARGE POSITIONS; A CONCRETE STORING RECEPTACLE ADJACENT THE UPPER END OF SAID PATH FOR RECEIVING CONCRETE FROM SAID MIXING TROUGH WHEN THE LATTER IS IN SAID DISCHARGE POSITION; LIFTING MEANS OPERATIVELY CONNECTED TO SAID MIXING TROUGH FOR LIFTING THE SAME FROM SAID LOWER CHARGING TO SAID UPPER DISCHARGE POSITION; AND CONTROL MEANS CONTROLLED BY THE AMOUNT OF CONCRETE IN SAID STORING RECEPTACLE AND OPERATIVELY CONNECTED TO SAID LIFTING MEANS FOR STOPPING OPERATION OF SAID LIFTING MEANS SHORTLY BEFORE SAID MIXING TROUGH REACHES ITS DISCHARGE POSITION WHEN SAID STORING RECEPTACLE IS SUBSTANTIALLY FILLED AND FOR CONTINUING OPERATION OF SAID LIFTING MEANS TO MOVE SAID MIXING TROUGH TO SAID DISCHARGE POSITION WHEN SAID STORING RECEPTACLE IS SUBSTANTIALLY EMPTY. 